Pedal Bass

At your risk.

You don't Fool Me - Queen

Bass stays the same while chords change.

The above example is very interesting as it is one of the very few compositions in history where the bass stays the same for a very long time.

Bass E, harmony E G B (E minor)

Bass E, harmony D #F A (D major)

Bass, harmony C E A (A minor)

It sounds very nice. A fine example of The Principle of Least Change in music.

Pedal Bass is one way of doing least change.

Other examples of Pedal Bass:

Us and Them - Pink Floyd

Against All Odds - Phil Collins at 1:02

Prelude in C minor - Chopin at beginning of chorus 0:40

Tocatta and Fugue in D minor - J. S. Bach at 0:26 to 0:38, 1:18 to 1:31, 6:49 to 7:04

One day we had a nice conversation with songwriter Mimis Plessas. He explained that pedal bass can be generalized to a constant melody while other parts are changing.

For example from the beginning, Just an Illusion - Imagination 

And here is a great example having pedal bass at a low part at 0:45, and at a high part at 1:22 (the synth melody at the right side of the stereo image).